[v2] netfilter: nft_nth: match every n packets

Message ID	20160727220053.GA26643@sonyv
State	Changes Requested
Delegated to:	Pablo Neira
Headers	show Return-Path: <netfilter-devel-owner@vger.kernel.org> Date: Thu, 28 Jul 2016 00:00:56 +0200 From: Laura Garcia Liebana <nevola@gmail.com> To: netfilter-devel@vger.kernel.org Subject: [PATCH v2] netfilter: nft_nth: match every n packets Message-ID: <20160727220053.GA26643@sonyv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 6a4dbe0..610e037 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1076,4 +1076,19 @@ enum nft_trace_types { __NFT_TRACETYPE_MAX }; #define NFT_TRACETYPE_MAX (__NFT_TRACETYPE_MAX - 1) + +/** + * enum nft_nth_attributes - nf_tables nth expression netlink attributes + * @NFTA_NTH_UNSPEC: unspecified attribute + * @NFTA_NTH_DREG: destination register (NLA_U32) + * @NFTA_NTH_EVERY: source value for every counter reset (NLA_U32) + */ +enum nft_nth_attributes { + NFTA_NTH_UNSPEC, + NFTA_NTH_DREG, + NFTA_NTH_EVERY, + __NFTA_NTH_MAX +}; +#define NFTA_NTH_MAX (__NFTA_NTH_MAX - 1) + #endif /* _LINUX_NF_TABLES_H */ diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 95e757c..6f00d01 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -474,6 +474,12 @@ config NFT_META This option adds the "meta" expression that you can use to match and to set packet metainformation such as the packet mark. +config NFT_NTH + tristate "Netfilter nf_tables nth module" + help + This option adds the "nth" expression that you can use to match a + packet every a specific given value. + config NFT_CT depends on NF_CONNTRACK tristate "Netfilter nf_tables conntrack module" diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 6913454..2378f00 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -80,6 +80,7 @@ obj-$(CONFIG_NF_TABLES_NETDEV) += nf_tables_netdev.o obj-$(CONFIG_NFT_COMPAT) += nft_compat.o obj-$(CONFIG_NFT_EXTHDR) += nft_exthdr.o obj-$(CONFIG_NFT_META) += nft_meta.o +obj-$(CONFIG_NFT_NTH) += nft_nth.o obj-$(CONFIG_NFT_CT) += nft_ct.o obj-$(CONFIG_NFT_LIMIT) += nft_limit.o obj-$(CONFIG_NFT_NAT) += nft_nat.o diff --git a/net/netfilter/nft_nth.c b/net/netfilter/nft_nth.c new file mode 100644 index 0000000..525da7a --- /dev/null +++ b/net/netfilter/nft_nth.c @@ -0,0 +1,123 @@ +/* + * Copyright (c) 2016 Laura Garcia <nevola@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/netlink.h> +#include <linux/netfilter.h> +#include <linux/netfilter/nf_tables.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/smp.h> +#include <linux/static_key.h> +#include <net/netfilter/nf_tables.h> +#include <net/netfilter/nf_tables_core.h> + +struct nft_nth { + enum nft_registers dreg:8; + u32 every; + atomic_t counter; +}; + +static void nft_nth_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct nft_nth *nth = nft_expr_priv(expr); + u32 nval, oval; + + do { + oval = atomic_read(&nth->counter); + nval = (oval+1 < nth->every) ? oval+1 : 0; + } while (atomic_cmpxchg(&nth->counter, oval, nval) != oval); + + memcpy(&regs->data[nth->dreg], &nth->counter, sizeof(u32)); +} + +const struct nla_policy nft_nth_policy[NFTA_NTH_MAX + 1] = { + [NFTA_NTH_DREG] = { .type = NLA_U32 }, + [NFTA_NTH_EVERY] = { .type = NLA_U32 }, +}; + +static int nft_nth_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_nth *nth = nft_expr_priv(expr); + + nth->every = ntohl(nla_get_be32(tb[NFTA_NTH_EVERY])); + if (nth->every == 0) + return -EINVAL; + + nth->dreg = nft_parse_register(tb[NFTA_NTH_DREG]); + atomic_set(&nth->counter, 0); + + return 0; +} + +static int nft_nth_dump(struct sk_buff *skb, + const struct nft_expr *expr) +{ + const struct nft_nth *nth = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_NTH_DREG, nth->dreg)) + goto nla_put_failure; + if (nft_dump_register(skb, NFTA_NTH_EVERY, nth->every)) + goto nla_put_failure; + + return 0; + +nla_put_failure: + return -1; +} + +static struct nft_expr_type nft_nth_type; +static const struct nft_expr_ops nft_nth_ops = { + .type = &nft_nth_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_nth)), + .eval = nft_nth_eval, + .init = nft_nth_init, + .dump = nft_nth_dump, +}; + +static const struct nft_expr_ops * +nft_nth_select_ops(const struct nft_ctx *ctx, + const struct nlattr * const tb[]) +{ + if (!tb[NFTA_NTH_DREG] || + !tb[NFTA_NTH_EVERY]) + return ERR_PTR(-EINVAL); + + return &nft_nth_ops; +} + +static struct nft_expr_type nft_nth_type __read_mostly = { + .name = "nth", + .select_ops = &nft_nth_select_ops, + .policy = nft_nth_policy, + .maxattr = NFTA_NTH_MAX, + .owner = THIS_MODULE, +}; + +static int __init nft_nth_module_init(void) +{ + return nft_register_expr(&nft_nth_type); +} + +static void __exit nft_nth_module_exit(void) +{ + nft_unregister_expr(&nft_nth_type); +} + +module_init(nft_nth_module_init); +module_exit(nft_nth_module_exit); + +MODULE_LICENSE("GPL");

[v2] netfilter: nft_nth: match every n packets

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